Fatto generale: 21049 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 21049 is an unremarkable number.
Trivia: 21049 is an uninteresting number.
Data storica: August 17th is the day in 986 that a Byzantine army is destroyed in the pass of Trajan's Gate by the Bulgarians under the Comitopuli Samuel and Aron.